pioneer in the region of the history of individual development), like Oskar Fraas, Griesebach, Sandberger, and others—generally take a more reserved and neutral position, because of the uncertainty of the facts and the inaccessibility of the problems; but it comes especially from those scientists who are inclined to adopt an origin of species through descent and even through development, yet refuse to explain it by the selection principle, and look for the essential cause of the development in the organisms themselves, without claiming to have themselves found these causes. Among the most prominent advocates of this view, we may name the late Sir Charles Lyell, Mivart, and
Richard Owen, in England; and in Germany, Alexander Braun, Ecker, Gegenbaur, Oswald Heer, W. His, Nägeli, Rütimeyer, Schaaffhausen, Virchow, Karl Vogt, A. W. Volkmann, Weismann, Zittel, and here also Moriz Wagner, and among the philosophers, Eduard von Hartmann. Many of these men are but little aware of the difference between the two questions: whether, on the one hand, the adoption of the origin of species through descent does not of itself involve the idea of a gradual development of one species from another, almost unobservable in its single steps; or, on the other hand, whether a descent of species through heterogenetic generation in leaps and through a metamorphosis of the germs, could be imagined. They consider descent and evolution as identical; and this identification is explainable so long as we are not in a condition to come nearer to the eventual causes of the supposed variation of species. But men are not wanting who put these questions clearly and plainly, and separate them distinctly from one another. Among them we may mention K. E. von Baer, Ed. von Hartmann and Wigand; of the latter we will have occasion to speak more in detail hereafter. Among them we find also scientists who answer the question in the sense of a new-modeling of the species, of a heterogenetic generation, and of a metamorphosis of germs. To this class belong especially Oswald Heer—"Urwelt der Schweitz" ("Antediluvian World in Switzerland"), Zürich, 1865, p. 590-604; Kölliker—"Ueber die Darwin'sche Schöpfungstheorie," ("Darwin's Theory of Creation"), Leipzig, 1864; "Morphologie und Entwicklungeschichte des Pennatulidenstammes nebst allgemeinen Betrachtungen zur Descendenzlehre,"
("Morphology and History of the Development of the Stem of the Pennatulidæ, together with General Remarks on the Descent Theory"), Frankfurt, 1872; and Heinrich Baumgärtner—"Natur und Gott" ("Nature and God"), Leipzig, Brockhaus, 1870. Heer has introduced into scientific language the term "new-modeling of the species," Kölliker that of a "heterogenetic generation," and Baumgärtner that of a "transmutation of the types through a metamorphosis of germs." Baer also is not averse to adopting the latter.
The botanist, Albert Wigand, of Marburg, takes a peculiar position. On one hand, the observation of the relationship of organic beings with one another leads him to adopt a common genealogy, a descent; on the other, the objections to adopting a descent of the species one from another appear to him insurmountable. In the first place, he sees all the species everywhere strictly limited—although in the second volume of his work, which appeared after the preceding lines were written, he again warns against a one-sided emphasizing of the invariability of species. In the second place, he sees so clearly, through the whole organic world, the differences, nay, the contrasts, of the species, in their building plan, in the numbers and conditions and positions of their parts, and in their mode of development, that it appears to him impossible to assume in the perfected organism a production of germs which in a course of generations, by a process even as gradual as possible, would grow into such an entirely new phenomenon as a new, even closely related, species would be. But if we adopt the theory of a heterogenetic generation, we explain by it the variety but not the similarity of species;
for a heterogenetic generation would in the new species make everything different from the old one—a conclusion, the necessity of which it would be difficult to show. For these reasons, he refers the descent of the organic beings, not to the series of the species, with their individuals already specified and defined, but to the series of primordial cells living free in the water. The earliest primordial cells represented only the common character of the whole organic world, and out of them the primordial cells of the animal and those of the vegetable kingdom were produced by dividing the cells; so that the first ones embraced only the general and primitive characteristics of the whole animal, the last ones those of the whole vegetable kingdom. Out of these primordial cells of the two kingdoms, those of the main types proceeded—(for instance, the primordial cells of the radiated animals, the vertebrates, etc., the gymnosperms, the angiosperms, etc.); out of them those of the classes—(for instance, the mammalia, the dicotyledons); out of them those of the orders—(for instance, the beasts of prey, rosifloræ); out of them those of the families (canina, rosaceæ); out of them those of the genus (canis, rosa); and out of them those of the species (canis lupus, rosa canina). Only when the primordial cells of the species had been produced, were they developed into finished representatives of the species; and when once these primordial cells of the species had been developed into finished and full-grown individuals of the species, their transmission took place in the manner well known to us. Wigand published his criticism of the Darwinian Theories in his larger work, "Der Darwinismus und die Naturforschung Newtons und Cuviers," ("Darwinism
and the Natural Science of Newton and Cuvier"), Braunschweig, Vieweg, Vol. I, 1874, Vol. II, 1876, and his own attempt at explanation in a smaller book, published at the same place in 1872: "Die Genealogie der Urzellen als Lösung des Descendenzproblems oder die Entstehung der Arten ohne natürliche Zuchtwahl" ("Genealogy of the Primordial Cells as a Solution of the Problem of Descent; or the Origin of Species without Natural Selection").
Whether this genealogy of the primordial cells found any followers, we do not know. None of the hypotheses thus far mentioned are so very far from having analogies in experience. The idea of a first development of the higher organisms out of their specific primordial cell, through all kinds of conditions of larvæ up to the finished form, demands of us the acceptance of monstrous improbabilities—(think, for example, of the first men, who, originating from a human primordial cell, grow in different metamorphoses of larvæ, first in the water and then on the land, until they appear as finished men). Moreover, the hypothesis, in claiming that a heterogenetic generation of one species from another must necessarily nullify all similarity between the organism of the child and that of the mother, is so little convincing, and shows—in the necessity of conceiving the universal type of organisms, the type of kingdoms, of main types, of classes, of orders, of families, of genera, and of species, as but individual existences which, in the form of cells and before the existence of the developed species, partly through many thousands of years, lead a real empiric and concrete life—such an abstract synthetical construction of nature, that
we are not astonished that the theory of the genealogy of primordial cells stands almost alone. On the other hand, Wigand's larger critical work rendered great service in clearing up the problems. It is true, his judgment appears in many single cases not at all convincing, since he often enough fights his adversaries with sophisms and deduces from the views of Darwin and Häckel conclusions to which they certainly do not lead. But in the majority of cases, his work is full of real convincing power, and with the breadth of its philosophical view and with the sharpness of its definitions, as well as with its abundance of philosophic and especially botanical teachings and their ingenious application, it is directly destructive to the use of the selection theory as the principal key to the solution of the problems. Eduard von Hartmann describes the work in his publication, "Wahrheit und Irrthum im Darwinismus," ("Truth and Error in Darwinism"), as a mile-stone which marks the limits where Darwinism as such passed the summit of its influence in Germany.